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Local Anomoly



Earlier today I was trying to work SO-50.  I completed one QSO on SO-50 the 
other day, have heard a few other stations, and had a partial QSO a day or 
two ago, so I know my equipment is capable, if marginal, for working SO-50.

Anyway, while SO-50 was up, I was listening for other stations (I heard one 
or two "out there", but not enough to copy a full callsign).  Then I tried 
finding my own downlink, which I did (or thought I did).

The pass was nearly over, so I had manually adjusted for doppler: downlink 
freq down to 436.7865 and the uplink up to 145.8516.  There I heard my own 
signal.  Weak, but clearly there.  No noticeable delay, but I figured it's 
a LEO, so not much expected.  Called CQ for a while, but no takers.  Well, 
SO-50 went well past LOS and I was still hearing myself.  Huh?

Equipment: FT-736R and a dual-band Ringo Ranger, using a Comet duplexer 
(antenna has a single connection while the radio has separate connections 
for each band).  Yes, this is a nice radio with a relatively lousy antenna 
system, but it's what I have right now.

Harmonic?  Well, 145.8516 x 3 = 437.5548, which is 0.7683 MHz away from 
436.7865.
Intermediate frequencies for the radio are 455 kHz and 13.69 MHz, plus 
47.43 MHz on 430.  I can't find any combination of those that make up the 
768.3 kHz difference.

Nearby freq pairs where I can hear myself:

tx 145.840 and rx 436.760
tx 145.850 and rx 436.781
tx 145.855 and rx 436.792

But I cannot hear myself transmitting on 145.860 anywhere near 436.802 +/- 
20 kHz, nor 145.835 and 436.750

Any ideas?

David, KY7DR
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